The gap for 'EU-15' is assessed by considering the sum of the gaps of the 15 EU Member States which are part of the burden-sharing agreement. Since Member States with a surplus can use any remaining allowances for their own purposes and not necessarily transfer them via the flexible mechanisms to compensate for Member States with a shortfall, a gap is also calculated for 'EU-15 (no overachievement)', where only shortfalls are considered, but not any surplus.